Flat panel displays such as a liquid-crystal display panel and a liquid-crystal projector substrate are conventionally broken so as to be divided into separate panels of a predetermined size after mother glass substrates are bonded each other in a manufacturing step. The process of breaking a brittle material substrate such as this mother glass includes a scribe process and a break process, and a scribe device is used in the scribe process.
FIG. 1 is an outlined perspective view showing an example of a conventional scribe device. This scribe device 100 retains a moving base 101 to be freely movable in y axis direction along a pair of guide rails 102a and 102b. A ball screw 103 is fitted to the moving base 101 with screwing each other. The ball screw 103 revolves due to drive by a motor 104, and moves the moving base 101 in the y axis direction along the pair of guide rails 102a and 102b. A motor 105 is provided on an upper surface of the moving base 101. The motor 105 rotates a table 106 on a xy plane and positions the table at a predetermined angle. A brittle material substrate 107 is placed on the table 106 and retained by a vacuum suction means and the like which are not shown in the figure. Two CCD cameras 108 for imaging alignment marks of the brittle material substrate 107 are provided in an upper portion of the scribe device.
A bridge 110 is installed by support poles 111a and 111b along x axis direction so as to stride the moving base 101 and the table 106 on the base in the scribe device 100. A scribe head 112 is able to move in the direction of x axis along a guide 113 included in the bridge 110. A motor 114 is a drive source for moving the scribe head 112 along the x axis direction. A tip holder 130 is attached to a tip portion of the scribe head 112 via a holder joint 120.
A conventional holder joint and tip holder attached to the scribe head 112 will be explained next. As an exploded perspective view shown in FIG. 2, the holder joint 120 has a bearing 121 at its upper portion, and has a holder unit 122 where its under portion is formed in a L-shape. A lateral portion of the holder unit 122 includes a positioning pin 123. The tip holder 130 retains a discoid wheel tip (hereinafter referred to as a tip merely) 131 rotatably as shown in FIG. 3 and FIG. 4. The tip 131 is retained rotatably at an end portion in centre of bottom by a pin (not shown in the figure), and the pin is prevented from dropping due to a catcher 132. The tip 131 rotates to form a scribe line with being pressed to contact a brittle material substrate. This tip holder 130 is positioned on the holder part 122 of the holder joint 120 by contacting its side surface with the positioning pin 123. Then the tip holder 130 is fixed to the holder unit 122 by a fixing bolt 133. The scribe head 112 retains the holder joint 120 and the tip holder 130 in its underneath so as to move up and down. The scribe head 112 includes an elevation unit for allowing the moving up and down such as, for example, an air cylinder using an air pressure control or an electric elevation unit employing a linear motor, internally. The elevation unit rotates the tip 131 on a surface of a brittle material substrate with pressing the tip at an appropriate pressure to contact the substrate, and forms a scribe line.
A scribe operation of the scribe device where electrical and mechanical adjustments necessary for the scribing operation is completed after assembling will be described next. FIG. 5A and FIG. 5B are flowcharts showing a procedure of this processing. Firstly, the brittle material substrate 107 is placed on the table 106 before the scribing operation starts as shown in FIG. 6 and is sucked and secured after being positioned (step S0). And then, in order to check a positioning status, positioning alignment marks 63a and 63b on two points in right and left parts on the substrate are imaged with being enlarged respectively by using two CCD cameras 108 installed in upper portion of the scribe device, and image processing is performed (step S1). Since the enlarged picture imaged above is respectively displayed on corresponding monitors, an operator is able to realize an accurate positioning operation with confirming the imaged pictures. The scribe device 100 detects magnitudes of an angular degree (θ) at which the substrate 107 inclines with respect to a line connecting the two CCD cameras, i.e., a reference line A and of misaligned placement of the substrate 107 with respect to an origin position as a reference of the table 106 by image processing (step S2). Progressing to step S3, the scribe device 100 corrects an incline angle θ of the table 106 on the basis of the detection result by means of rotation of the motor 105 so that the angle can be zero. The misalignment with respect to the origin position of the table 106 can be corrected as follows. Regarding the y axis direction, the table 106 is moved to the y axis direction only in a distance equal to a component of the y axis direction of aforementioned misalignment distance, and regarding the x axis direction, a position of the scribe head 112 is moved only in a distance equal to a component of the x axis direction of aforementioned misalignment distance. In addition, there is another correction method described below. A start position of the scribe can be shifted by the scribe device, which divides aforementioned misalignment distance into an x axis component and a y axis component and corrects values of the respective axis components of a position data of the start position of the scribe operation. This provides an equal effect.
It is necessary to perform the correction operation for aforementioned misalignment distance every time a substrate to be scribed is replaced. Upon finishing the correction operation, the scribe operation starts from a desired position. The scribe device 100 lowers the tip holder, contacts the tip to a substrate and moves the tip holder to rotate the tip and to perform a normal scribe (steps S5 to S7). After forming a scribe line, the scribe device 100 raises the tip holder (step S8), then relatively moves the substrate (step S9), and the operation returns to step S5.
The moving of the substrate shown in step S9 will be explained in detail with referring to FIG. 5B. The scribe device 100 judges whether or not a flag FX that is control data in a control program is zero first (step S10). This flag FX is a flag placed in rotating the table and indicates zero after initialization. When the flag FX indicates 0, it is judged whether or not the scribing in the x axis direction has been completed progressing to step S11. When not completed, the scribe device 100 relatively moves the substrate by moving the table 106 (step S12), and the same operation is repeated returning to step S5. This allows the scribe in the x axis direction to be completed by repeating this loop. When the scribe in the x axis direction has been completed, the scribe device 100 sets the flag FX to be 1 progressing to step S13 and turns the table 106 in right direction at 90 degrees progressing to step S14. The scribe device judges whether or not scribe in the y axis direction has been completed at step S15, and moves the table 106 progressing to step S16 when not completed, and the operation returns to step S5. Since the flag FX is placed after the scribe in the x axis direction is completed, the scribe device 100 judges whether or not the scribe in the y axis direction has been completed progressing from step S10 to step S15. When the scribe has not been completed, the scribe device 100 relatively moves the substrate in parallel to the y axis direction only in necessary move distance (step S16). After that, the same scribe operation is repeated returning to step S5 again. When determining that formation of the entire scribe line in the y axis direction has been completed at step S15, the scribe device 100 turns the table 106 in left direction at 90 degrees and completes the scribe operation. The scribe device 100 resets the flag FX, and the substrate is released from the suction and removed from the table 106 (step S17). When another substrate is placed on the table subsequently, the scribe operation is performed also in accordance with the same procedure.
It is required to perform the correction operation for misalignment distance by a method mentioned below when the holder joint 120 is installed to the newly produced scribe device 100, when, after uninstalling the tip holder 130, scribe head 112 and holder joint 120 to which the tip 131 is installed for the purpose of adjustment, fixing, or change while using the scribe device, they are installed and used again after the adjustment, and when another component is installed and used after replacement. Supposing following adjustments are already completed in this case for ease of explanation, the explanation will be continued. It is supposed that a central coordinate of an imaged picture of one camera among the two CCD cameras is adjusted so as to agree with the origin position necessary for the formation of the scribe line and that a scribe line formed by the tip after installing components such as the tip holder is preliminarily adjusted so as to be parallel with the reference line of the x axis direction of the table.
Test scribe is required in order to accurately detect misalignment between an origin position of a drive system of the scribe device 100 and a start position where the formation of a scribe line actually starts with the tip 131 on a substrate. When performing the test scribe, an operator places a dummy substrate other than a normal mother substrate on the table 106 and preprocessing from step S0 to S3 is performed. FIG. 7 is a pattern diagram showing a relationship between a scribe line formed on the dummy substrate at the test and a central coordinate P0 of an alignment mark of an imaged picture of a CCD camera. When each offset of the scribe head 112, the holder joint 120, and the tip holder 130 is corrected and cancelled, the scribe device 100 is able to start the scribe from the central coordinate P0.
Electrical and mechanical errors, however, exist and values of the errors are different in respective assembly components, and consequently the scribe from the central coordinate P0 cannot be performed if errors after installation are not measured again and a necessary correction operation is not completed. The operator lowers the tip holder 130 and contacts the tip to the dummy substrate in this condition (steps S5′ and S6′). And, the operator performs the test scribe on the dummy substrate to form one scribe line (S7′). After that, the operator raises the tip holder (S8′) and measures misalignment distance (S9′). It is supposed here that a scribe start position (X,Y) is a position P1(X,Y)=(4,3) as shown in FIG. 7. This position can be measured by using a picture imaged by the CCD cameras 108.
The operator measures a misalignment distance from the position P1 to the central coordinate P0 next (S9′). This misalignment distance is a value to be cancelled as an offset, and a correction operation is performed by using the value as a correction value (S10′). The operator then removes the dummy substrate from the table and the correction operation is completed (S11′). After that, the same operation is repeated returning to step S0. According to this, the scribe can be started from the central coordinate P0 in the normal scribe after step S5 shown in FIG. 5A.
When the correction operation is performed in this manner, a scribe line on the brittle material substrate 107 is formed accurately on a position of a predetermined line (for example, a line B in FIG. 6) by performing the preprocessing of steps S1 to S3 every time a substrate to be scribed is changed after the correction operation and a scribe operation is repeated with sequentially changing a scribe start position with respect to the same substrate 107 (steps S5 to S9).
Since worn after scribing a brittle material substrate for a predetermined distance and deteriorating its performance, the tip needs to be replaced regularly (Patent document 1). When replacing a consumable tip in a conventional scribe device, an operator uninstalls the tip holder 130 from the scribe head 112 first. The operator uninstalls the worn tip 131 from the uninstalled tip holder 130 and installs a new tip to the tip holder 130 next. After that, the operator installs the tip holder 130 to the scribe head 112 again to complete a replacement operation. Since errors (offset) occur at an installation position of the tip even when one of the tip, the tip holder, and the scribe head is replaced, the test scribe and the subsequent correction operation (steps S5′ to S11′) are required to balance the offset out.
The offset occurred in replacement of peripheral components of the scribe head is corrected as described above, and, after performing the preprocessing from step S0 to step S3 with respect to a normal mother substrate, the necessary number of scribe lines are formed by repeating the sequential scribe-related operation from step S5 to step S9.
The scribe device 100 in which the scribe head moves in the x axis direction and the table moves in the y axis direction and turns has been described here. Some scribe devices, however, have a table which moves in the x and y axis directions and also turns (Patent document 2). In addition, other scribe devices have tables which move in the x and y axis directions but no turn mechanism. Furthermore, there is a type of a scribe device in which a table is secured and a scribe head moves in the x and y axis directions (Patent document 3).
As a modified example of the scribe device shown in FIG. 1, there is a type of a scribe device which does not have a turn table on the moving base 101 and directly places the brittle material substrate 107 on the moving base (device type 1). As further another modified example, there is a type of a scribe device which has a secured table 106 in FIG. 1 and includes a drive mechanism for moving the bridge 110 with the support poles 111a and 111b in the y axis direction (device type 2, for example, Patent document 4). This case requires the following scribe operation. That is to say, since the incline angle θ of the substrate 107 detected at step S2 in FIG. 5A cannot be corrected, only a correction operation for misalignment distance of the substrate is performed at step S3. A scribe operation according to the method of linear interpolation explained by referring to FIG. 6 is performed instead of the correction of θ in this scribe device. Specifically, when only the scribe head 112 merely moves in the x axis direction in a case where a regular scribe line is assumed to be formed at a position of a straight line B, nothing can be obtained but a line of a straight line A. This scribe device moves the table 106 in the case of the device type 1 and the bridge 110 in the case of the remaining device type 2, respectively, concurrently with the moving of the scribe head in the x axis direction. An inclined scribe line B can be formed in this manner. The move distance of the concurrently moving depends on a magnitude of the incline angle θ. In the inclined scribe line, the scribe head 112 and the table 106 (or the bridge 110) share the move distances equal to the base and the height of a triangle formed at the incline angle θ, and, in other words, it can be realized by repeating a minimally stepwise linear move formed of lines in two directions.    Patent document 1: Japanese Patent Publication No. 3074143    Patent document 2: Japanese Unexamined Patent Publication No. 2000-119030    Patent document 3: Japanese Unexamined Patent Publication No. 2000-086262    Patent document 4: Japanese Unexamined Patent Publication No. 2000-264657